| use rustc_ast as ast; |
| use rustc_middle::mir::interpret::{ |
| truncate, Allocation, ConstValue, LitToConstError, LitToConstInput, Scalar, |
| }; |
| use rustc_middle::ty::{self, ParamEnv, TyCtxt}; |
| use rustc_span::symbol::Symbol; |
| use rustc_target::abi::Size; |
| |
| crate fn lit_to_const<'tcx>( |
| tcx: TyCtxt<'tcx>, |
| lit_input: LitToConstInput<'tcx>, |
| ) -> Result<&'tcx ty::Const<'tcx>, LitToConstError> { |
| let LitToConstInput { lit, ty, neg } = lit_input; |
| |
| let trunc = |n| { |
| let param_ty = ParamEnv::reveal_all().and(ty); |
| let width = tcx.layout_of(param_ty).map_err(|_| LitToConstError::Reported)?.size; |
| trace!("trunc {} with size {} and shift {}", n, width.bits(), 128 - width.bits()); |
| let result = truncate(n, width); |
| trace!("trunc result: {}", result); |
| Ok(ConstValue::Scalar(Scalar::from_uint(result, width))) |
| }; |
| |
| let lit = match (lit, &ty.kind()) { |
| (ast::LitKind::Str(s, _), ty::Ref(_, inner_ty, _)) if inner_ty.is_str() => { |
| let s = s.as_str(); |
| let allocation = Allocation::from_byte_aligned_bytes(s.as_bytes()); |
| let allocation = tcx.intern_const_alloc(allocation); |
| ConstValue::Slice { data: allocation, start: 0, end: s.len() } |
| } |
| (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) |
| if matches!(inner_ty.kind(), ty::Slice(_)) => |
| { |
| let allocation = Allocation::from_byte_aligned_bytes(data as &Vec<u8>); |
| let allocation = tcx.intern_const_alloc(allocation); |
| ConstValue::Slice { data: allocation, start: 0, end: data.len() } |
| } |
| (ast::LitKind::ByteStr(data), ty::Ref(_, inner_ty, _)) if inner_ty.is_array() => { |
| let id = tcx.allocate_bytes(data); |
| ConstValue::Scalar(Scalar::Ptr(id.into())) |
| } |
| (ast::LitKind::Byte(n), ty::Uint(ast::UintTy::U8)) => { |
| ConstValue::Scalar(Scalar::from_uint(*n, Size::from_bytes(1))) |
| } |
| (ast::LitKind::Int(n, _), ty::Uint(_)) | (ast::LitKind::Int(n, _), ty::Int(_)) => { |
| trunc(if neg { (*n as i128).overflowing_neg().0 as u128 } else { *n })? |
| } |
| (ast::LitKind::Float(n, _), ty::Float(fty)) => { |
| parse_float(*n, *fty, neg).map_err(|_| LitToConstError::UnparseableFloat)? |
| } |
| (ast::LitKind::Bool(b), ty::Bool) => ConstValue::Scalar(Scalar::from_bool(*b)), |
| (ast::LitKind::Char(c), ty::Char) => ConstValue::Scalar(Scalar::from_char(*c)), |
| (ast::LitKind::Err(_), _) => return Err(LitToConstError::Reported), |
| _ => return Err(LitToConstError::TypeError), |
| }; |
| Ok(ty::Const::from_value(tcx, lit, ty)) |
| } |
| |
| fn parse_float<'tcx>(num: Symbol, fty: ast::FloatTy, neg: bool) -> Result<ConstValue<'tcx>, ()> { |
| let num = num.as_str(); |
| use rustc_apfloat::ieee::{Double, Single}; |
| let scalar = match fty { |
| ast::FloatTy::F32 => { |
| num.parse::<f32>().map_err(|_| ())?; |
| let mut f = num.parse::<Single>().unwrap_or_else(|e| { |
| panic!("apfloat::ieee::Single failed to parse `{}`: {:?}", num, e) |
| }); |
| if neg { |
| f = -f; |
| } |
| Scalar::from_f32(f) |
| } |
| ast::FloatTy::F64 => { |
| num.parse::<f64>().map_err(|_| ())?; |
| let mut f = num.parse::<Double>().unwrap_or_else(|e| { |
| panic!("apfloat::ieee::Double failed to parse `{}`: {:?}", num, e) |
| }); |
| if neg { |
| f = -f; |
| } |
| Scalar::from_f64(f) |
| } |
| }; |
| |
| Ok(ConstValue::Scalar(scalar)) |
| } |